BMR Calculator
Your basal metabolic rate (BMR) is an estimate of the calories your body uses in a day at complete rest, to keep breathing, circulating blood and holding its temperature. Enter your details to estimate yours. The math runs in your browser: nothing you type is sent anywhere.
Your estimated BMR
Fill in the form and press Calculate to see your estimated BMR. Add your body-fat percentage to also see the Katch-McArdle estimate.
- BMR (Mifflin-St Jeor)
- BMR (Katch-McArdle)
These are estimates, not medical or dietary advice. How we estimate, with sources
BMR vs TDEE: what's the difference?
BMR is what you burn at rest. TDEE, your total daily energy expenditure, adds everything you do on top: walking, training, even digesting food. To estimate it, BMR is multiplied by an activity factor; in this app that is 1.3 to 1.75, depending on how many days a week you train. Use TDEE, not BMR, to plan how much to eat.
The formulas we use
Mifflin-St Jeor is the equation the app uses: 10 × weight in kg + 6.25 × height in cm − 5 × age in years, then + 5 for men or − 161 for women. A systematic review found it came within 10% of measured resting energy for more people than the other common equations.
Katch-McArdle uses lean body mass instead of sex, age and height: 370 + 21.6 × lean mass in kg, where lean mass is your weight minus your body fat. It is only as good as your body-fat number, which is why it is optional here.
Harris-Benedict, from 1918, is the oldest of the three and many calculators still use it. We don't: in the same review it was right less often than Mifflin-St Jeor. Every equation is cited on the sources page.
Why BMR estimates vary between calculators
Calculators use different equations (Mifflin-St Jeor, Harris-Benedict, Katch-McArdle), round differently and sometimes already multiply by an activity factor without saying so. Even the best equation describes groups of people, so your measured resting energy can be above or below any of them. Treat every result as an estimate.
Why your BMR changes
Weight, age and the share of your weight that is lean mass all enter the equations, so your BMR estimate moves when they do. Losing weight lowers it a little, and so does getting older. That is one reason the app re-estimates your targets every week from your weight trend instead of keeping a fixed number.
FAQ
What is BMR?
BMR, or basal metabolic rate, is the energy your body uses in a day at complete rest: breathing, circulation, keeping warm and keeping your organs running. It does not include any movement or exercise. Calculators estimate it from your weight, height, age and sex, or from your lean body mass.
BMR vs TDEE: what's the difference?
BMR is the energy you use at rest. TDEE, total daily energy expenditure, is BMR plus everything you do: daily movement, training and digesting food. The app estimates TDEE by multiplying BMR by an activity factor from 1.3 to 1.75, depending on your training days. Plan your eating around TDEE, not BMR.
Which BMR equation is most accurate?
In a systematic review of the common equations, Mifflin-St Jeor came within 10% of measured resting energy for more people than the others, including Harris-Benedict, which is why we use it. If you know your body-fat percentage well, Katch-McArdle is a reasonable second opinion. No equation is exact for everyone.
Can I use my BMR to lose weight?
BMR on its own is not a calorie target, because it leaves out everything you burn by moving. Start from your TDEE instead, then eat somewhat less than that. The app aims at losing about 0.5% of your body weight a week and checks your weekly trend to see whether the estimate needs to change.
Is BMR different for women?
In the Mifflin-St Jeor equation, yes: it subtracts 161 kcal for women and adds 5 for men, so at the same age, height and weight a woman's estimate is 166 kcal a day lower. Katch-McArdle has no sex term at all; it works from lean mass, so any difference comes only from body composition.
What is a normal BMR?
There is no single normal value, because BMR depends on your size, age and sex. As examples from Mifflin-St Jeor: a 30-year-old woman at 165 cm and 60 kg gets about 1,320 kcal a day, and a 30-year-old man at 180 cm and 80 kg about 1,780. Yours can be higher or lower.
Track this in the app
Log your food and your lifts in one place. Your estimates adjust each week to how you eat and train.
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